In ball valve assemblies designed for use with relatively high pressure fluids (i.e., gases or liquids) a ball valve is generally supported for rotation in a valve housing by at least one trunnion that extends through the housing into the valve chamber. In many designs the ball valve is actuated between open and closed positions via a rotary spindle (or stem) that extends through a bore in the valve housing and into the ball.
The other end of the spindle extends out of the housing where it is connected to an actuator such as a lever or a motor. The spindle is supported in the housing bore by a bonnet that is fastened to the housing exterior. The bonnet serves to retain the spindle in the housing and generally has a lower surface that is designed to abut an anti-blowout shoulder on the spindle. The abutment of the shoulder and the bonnet surface prevent significant movement of the spindle out of the housing.
A ball valve assembly of this kind is assembled by inserting the components in a certain sequence. Typically one of the valve seats is first inserted into the valve chamber followed by the ball valve and then the opposite seat. The trunnion is fitted into the ball through an aperture in the housing and then spindle and bonnet are inserted into the bore together. The end of the spindle is received in a socket in the ball valve and the bonnet is then fastened securely to the outside of the housing.
There remains a need for an improved ball valve assembly and a method for assembling a ball valve assembly. The present invention satisfies this need and provides other benefits and advantages in a novel and unobvious manner.